Alopecurus lanatus from Western Turkey looks very similar, and there's only ~30 species in the genus, so that's something to work with, thanks.
ClifflineGardens dot com
Fort Collins, CO zone 5b
This is another green roof volunteer, found in two places on a 5th floor green roof, near Bolingbrook. I believe it is Sagina procumbens (Pearlwort), relocated to my windowsill for further study. Charming, little, moss-like plant. For scale, the Sedums in the photo are S. dasphyllum and S. hispanicum purpureum. This is perhaps not a flashy species, but I find it very interesting, and I'm incredibly enthused about any green roof volunteer that can behave itself.
I believe my grass species to be Koeleria glauca. It is either a cultivar, or the growth response to being in a harsh environment. If it is a cultivar, then someone planted it intentionally, if it isn't, then it's habit is from being in such a harsh environment. Like I said, there's one on my windowsill now, so we'll see how it does. The species is non-invasive.
From crocus.co.uk"A tuft-forming evergreen grass with pretty, grey-green leaves, and dense silver green flower spikelets that fade to buff in the autumn. It prefers dry soils and will tolerate an exposed spot, but it is short lived, so may need to be replaced in a few years. It makes a striking edging to a path or border, and looks great in a gravel garden"
Sagina can be terrible menace amongst more choice alpine plants, but might bind together plants on a Green Roof where conditions are harsh. I'd be a bit wary of it though!
Dr. Timothy John Ingram
Faversham, Kent, UK
I garden in a relatively hot and dry region (for the UK!), with an annual rainfall of around 25", winter lows of -10°C and summer highs of 30°C.